High-Precision Refractive Index-Based Microparticle Sorting Using Airy Beams

Precise sorting of microparticles based on their refractive indices is crucial for various applications, including hematological diagnostics, early cancer detection, and microplastic identification. Conventional imaging methods struggle to effectively distinguish particles with similar sizes but different compositions. Existing techniques, such as optical fibers, optical lattices, and plasmonic optical tweezers, often face challenges in achieving high sorting precision. Here we propose an approach utilizing Airy beams to enable high-precision refractive index-based particle sorting. By leveraging the lateral acceleration and nondiffractive properties of Airy beams, we demonstrate robust sorting of particles with sub-0.03 refractive index differences in a label-free and contactless manner. Experimental results show that particles made of various materials, including polystyrene (PS), polyvinyl chloride (PVC), silica (SiO₂), and poly(methyl methacrylate) (PMMA), can be effectively separated based on their inherent refractive indices. The proposed method provides a versatile and efficient tool for particle manipulation and sorting, with potential applications in particle characterization, bioseparation, and microfluidics.